Marine fouling is a major problem in the transport of materials by sea as it can raise fuel consumption by as much as 30%. Environmentally friendly coatings that protect the hulls of ships below the waterline against fouling by seaweed, barnacles, and other organisms are currently sought by the shipping industry. Fouling by these organisms produces additional drag on the ship, thereby increasing operating and maintenance costs.
Antifouling paints containing tin and copper biocides are currently used because of their effectiveness against most forms of marine fouling. Many of these biocidal organometallic compounds are environmentally persistent. They can cause damage to the ecosystem and enter the food chain. A total ban by the International Maritime Organization on the presence of tributyltin (TBT) antifoulants on vessel hulls will be effective in 2008, and copper-based coatings are expected to face similar restrictions in the near future.
Non-toxic “fouling-release” or “fouling-repellant” coatings are one class of alternatives to biocidal coatings. Silicone-based paints are commercially available, but do not satisfy many desired performance characteristics. The soft silicones do not withstand the rigorous demands of the marine environment, do not sufficiently and consistently self-clean, or, due to polymer restructuring or other degradation pathways, lose many of the desirable surface properties with time and exposure to marine organisms.
Several fouling release (FR) coating systems are commercially available, mostly based on silicone polymers, yet none meet all of the desired performance characteristics. Many commercially available coating systems lack the toughness required to withstand the rigorous physical demands of the marine environment, do not sufficiently and consistently self-clean, and due to polymer restructuring or other degradation pathways, lose many of the desirable surface properties with time and exposure to the marine environment.
Accordingly, what is needed is a material that lowers the strength of adhesion between fouling organisms and a surface, for example, a marine surface. What is also needed is a surface that is resistant to marine biofouling, for example, fouling by marine organisms such as zoospores and diatoms (unicellular algae). The diversity of fouling organisms and environmental conditions worldwide makes the task of developing a coating that resists fouling and/or self-cleans challenging, and novel non-toxic solutions to the problems of biofouling are urgently needed.